V4+R VRF 50/60Hz
201702 15
Part 2 - Component Layout and Refrigerant Circuits
Key components:
1. Oil separator:
Separates oil from gas refrigerant pumped out of the compressor and quickly returns it to the compressor. Separation
efficiency is up to 99%.
2. Accumulator:
Stores liquid refrigerant and oil to protect compressor from liquid hammering.
3. Electronic expansion valve (EXV):
Controls refrigerant flow and reduces refrigerant pressure.
4. Four-way valve ST1:
Controls refrigerant flow direction of the left heat exchanger. When closed, the left heat exchanger functions as a
condenser; when open, the left heat exchanger functions as an evaporator.
5. Four-way valve ST2:
Controls refrigerant flow direction of the right heat exchanger. When closed, the right heat exchanger functions as a
condenser; when open, the right heat exchanger functions as an evaporator.
6. Four-way valve ST3:
When the system is in total cooling mode, ST3 is open. When the system is in total heating mode or mixed mode, ST3
is closed.
7. Solenoid valve SV2:
Protects the compressor. If compressor discharge temperature rises above 100°C, SV2 opens and sprays a small
amount of liquid refrigerant to cool the compressor. SV2 closes again once the discharge temperature has fallen
below 90°C.
8. Solenoid valve SV4:
Returns oil to the compressor. In single outdoor unit systems: opens once the compressor has run for 200 seconds
and closes 600 seconds later. In systems with multiple outdoor units: each unit's SV4 opens for 3 minutes every 20
minutes.
9. Solenoid valve SV5:
Enables fast defrosting. During defrosting operation, opens to shorten the refrigerant flow cycle and quicken the
defrosting process. Closed in cooling mode.
10. High and low pressure switches:
Regulate system pressure. When system pressure rises above the upper limit or falls below the lower limit, the high or
low pressure switches turn off, stopping the compressor. After 10 minutes, the compressor restarts.
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